NASA-led Analysis Reveals Sudden Change in Global Sea Level Last Year, Puzzles Scientists
NASA satellites are always on the lookout for interesting insights from Earth as well as space. Recently, they provided data to experts, which showcased a striking development that happened in oceans all through 2024, according to The Cool Down.
The data revealed that not only have global sea levels increased over the last year, but the rise has been more than what was expected. Researchers claim that global sea levels elevated by 0.23 inches in 2024, which they thought would be 0.17 inches.
Experts think that thermal expansion is responsible for rising global sea levels, according to NASA. Thermal expansion happens when oceans enlarge because of heating up. The rising sea levels did not stun researchers because the trend over the years has been towards this phenomenon. "The rise we saw in 2024 was higher than we expected," said Josh Willis, a sea level researcher at NASA’s Jet Propulsion Laboratory in Southern California. "Every year is a little bit different, but what’s clear is that the ocean continues to rise, and the rate of rise is getting faster and faster."
Researchers also noted that in 2024, the thermal expansion contribution to sea level rise increased. In the past, sea level rise was mostly attributed to processes like melting, where water from land through glaciers and ice came into the ocean. Data indicates that during this period, only one-third of the increase happened due to the expansion of warm water bodies. In 2024, this jumped to two-thirds as per NASA's analysis.
Experts expected this because 2024 was deemed to be the hottest year on record. Thus, oceans heating up more than usual and expanding was not surprising. Nadya Vinogradova Shiffer, head of physical oceanography programs and the Integrated Earth System Observatory at NASA Headquarters in Washington, claims these are the highest sea levels they have recorded in the last three decades.
NASA experts think that there are several ways in which heat is making its way into global oceans. Seawater arranges itself into different layers, based on factors like temperature and density. Warmer water is on top because it is lighter and less dense than the colder water. In most places, heat manages to move slowly through these layers and ultimately reach the surface. The heat then facilitates the expansion.
In certain places, the mixing could be a bit different. Strong winds could agitate the layers so much that they get subjected to heat through vertical mixing. Here, the layers themselves begin clashing with each other, causing heat as well as any other constituent to mix at a faster rate, according to Science Direct. The phenomenon can be noted during storms and hurricanes.
NASA started keeping records of global sea levels in 1993, according to ABC News. Since then, sea levels have risen by around four inches. The National Oceanic and Atmospheric Administration claims that sea levels have risen by somewhere between eight and nine inches since the 1880s. Experts believe that climate change, facilitated by humans, is the primary reason behind the unprecedented rise in sea levels.